Valentia Case-Rap foldable 3D printer

In the summer of 2016, browsing in Thingiverse I came across the Case-Rap 1.0 foldable 3D printer by jlguils. I liked the design strategy of dividing the structure in parts that, when folded, transformed themselves into a portable case. And started to develop my own custom version: the Valentia Case-Rap foldable 3D printer.

Mysterious z ribbing with PLA... solved!

I've been having consistent z ribbing on different custom printers since a year or so...
No matter what I've tried (z wobble isolator, z axis strabilizer, threaded rod diameter/pitch changed, etc.).
Yesterday my heated bed's MOSFET failed while printing yet another calibration cube and guess what... NO Z RIBBING!!!

Arduvision (II): OV7670 + FIFO module and arduino Mega

After several people asking for instructions to use an Arduino Mega to interface the ov7670 sensor, I decided to publish a tutorial about it...

Simple passive mono/stereo to stereo audio mixer circuit

A while ago I needed a very simple pasive miker to join one stereo and two mono signals together before amplifying them...

There is some mixed information on how to properly connect a mono signal to a stereo input, but most of it uses active mixing.

Repair faulty HC-SR04 ultrasonic sensor (solve erratic no-readings problems)

Recently I got some of these cheap sensors from Chinese suppliers, for a workshop I had to teach.

A couple of students reported that their sensors were behaving in an erratic way, sometimes working, then stopping again, the working...

After replacing them with more expensive ones bought at a local store, I decided to try fixing the faulty ones...

DIY PCBs on the cheap: toner transfer with Box Packing Tape and a Hair Straightener / Iron

A few months ago I started to design an affordable 2WD Robot Kit to teach 20 students in a workshop in the AVM Master, at the Universidad Politécnica de Valencia, Spain.

That means also making about 100 tiny PCBs!

Arduvision (I): embedded computer vision with arduino

Ok, its time to share stuff again.

I've spent most of this year's (2014) summer learning how to use a CMOS sensor together with an arduino (ATmega328p) microcontroller, in the process of developing some personal projects.

This is the first of a series of articles to publish my experiencies, and hopefully save someone's time.

In this first post, I'll just release the minimal info that may let you start right away experimenting without reading about how things work. In further articles I'll make detailed explanations of the hardware and software, and the decisions and reasons that led me to my current setup. However, at the end of this post, you may find links to useful documentation.